A metal-oxide-semiconductor (MOS) transistor is one of the most important devices in modern integrated circuits. A MOS transistor usually includes a semiconductor substrate, gate structures on a top surface of the semiconductor substrate, and sour/drain doped regions in the semiconductor substrate on two sides of each gate structure. Each gate structure includes a gate dielectric layer on the top surface of the semiconductor substrate, and a gate electrode layer on the gate dielectric layer.
In a MOS transistor, a voltage is applied to a gate structure, to regulate channel currents under the gate structure and generate on/off signals.
However, semiconductor devices formed by the MOS transistors in the current technology have poor performances.